Nearly every Houston house runs flexible duct — a wire helix, a plastic inner liner, a fiberglass blanket and a foil jacket — through an attic that passes 120°F every summer. It is rated for fifteen to twenty-five years. A cleaning crew that arrives to find duct past that age, or duct that has been wet, should stop and say so. This page is what they should say.
Heat is the enemy. Year after year of attic summers make the inner liner brittle and the adhesive that holds the layers together let go. The liner tears, or bunches up inside the jacket like a sock pushed down a leg, and the airflow through that run drops by half while the register still blows something. The fiberglass blanket compresses where the run sagged over a joist. The outer jacket splits and the fiberglass is exposed. Cold supply air then meets warm attic air at the bare fiberglass, hits the dew point, and the run sweats on the inside — a musty smell when the system starts, a water spot on the ceiling below the sag.
None of that is cleanable. A brush run through a brittle liner tears it. Cleaning duct that is delaminating is paying to hasten the replacement.
Harris County’s median home was built in 1988; more than half the county’s houses predate 1990. Fort Bend and Montgomery counties’ medians are 2005 and 2004. Between them, an enormous number of Houston homes are on original flex duct that is at or past its rated life. Before booking a cleaning on a house older than about twenty years, someone should go into the attic and look: split jackets, exposed fiberglass, a liner that crackles when squeezed, a run that has collapsed. Any of those turns the appointment into an assessment, and the honest quote is for replacement.
Then the flood rule, which is absolute. Flex duct or ductboard that has been under water, or soaked from above by a roof failure, is replaced. It cannot be dried and it cannot be cleaned to any standard; wet fiberglass grows within days in Houston humidity. The air handler is inspected by a licensed contractor. Mold inside the system above 25 square feet is separately licensed remediation in Texas. After Harvey put water into more than 150,000 Harris County homes, after Beryl and the 2024 derecho put roofs on attic floors, a lot of ductwork in this metro should have been replaced and some of it was cleaned instead. This site does not refer a cleaning of a flooded system.
Replacing the ductwork is air conditioning contracting and needs a TDLR license; it is not a duct cleaning crew’s job and this site does not quote it. For orientation, Houston HVAC contractors publish roughly $3,000 to $6,000 for a small single-story house, $5,000 to $10,000 for 1,500 to 2,500 square feet, and $7,000 to $15,000 or more for larger two-system homes, depending on how many runs, whether the plenums go too, and how bad the attic is. A cleaning that costs $700 and buys three more summers on duct that is already failing is not a saving against that; it is a delay.
What a duct cleaning contractor can honestly do on an old system is the assessment: photograph the runs, squeeze the liner, report what fraction is past saving, and either clean what is sound or hand the job to a licensed contractor. Ask for that on the call if the house is older than twenty years.
If nobody has replaced them, they are the age of the house. A new air handler does not mean new ductwork; installers often reuse the runs. Look for a jacket that is dull, stiff and split rather than shiny and pliable.
More likely a crushed or collapsed run, or a liner that has bunched. A cleaning will not fix airflow that is blocked by the duct itself. Someone needs to look at that run in the attic.
Often, yes, if the plenums and the rest are sound. That is a licensed HVAC job, quoted per run. A cleaning contractor who finds two bad runs among twelve should say so rather than clean all twelve.
Get a licensed contractor to inspect the system. If the duct was wet and is still in place, it is very likely growing, and the answer is replacement whatever it smells like today.
Duct that passes the age test gets cleaned the full way.
A gnawed jacket is a repair plus a cleaning, not one or the other.
Three floods since 2015. The page about what that does to attic systems.
Say the age of the house and which part of the metro. The contractor covering your zone looks before quoting, and tells you if the honest answer is replacement.
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Houston Duct